Thermo-Responsive Shape Memory Effect and Conversion of Porous Structure in a Polyvinyl Chloride Foam

Abstract

In this paper, a thermo-responsive shape memory effect in a polyvinyl chloride thermoset foam is characterized. Excellent shape recovery performance is observed in foam samples programmed both at room temperature and above their transition temperature. The conversion of porous structures in the foam from closed-cell to open-cell after a shape memory effect cycle is revealed via a series of specially designed oil-dripping experiments and optical images of the micro pores. Programming the strain higher than 20% results in an apparent increase in open-cell level, whereas programming temperatures have almost no influence.

Thermo-Responsive Shape-Memory Polyurethane Foams from Renewable Lignin Resources with Tunable Structures–Properties and Enhanced Temperature Resistance

“…This thermomechanical cycle was repeated three to four times to investigate the shape memory behavior of PUFs and their temperature-programmability. 8,12,46,47 Note, compressive stretch ratio (%) was reported, which is the ratio between of the final length (l) to the initial length (L) of the sample after compressive deformation.…”

“…As displayed below, one thermomechanical cycle included four steps: (1) the samples were heated up to a temperature of 20 °C above its T g and equilibrated for 10 min; (2) the samples were then uniaxially compressed to reach the required maximum axial compressive stretch ratio (λ = 100–50%) with a constant stretch rate (10%/min); (3) the samples were quickly (50 °C/min) cooled down to room temperature (< T g 60 °C) using liquid nitrogen-assisted cooling while keeping the programmed shape and then the force was released; and (4) the samples were reheated up to T = T g + 20 °C without applying force and allowed to recover for 10–20 min. This thermomechanical cycle was repeated three to four times to investigate the shape memory behavior of PUFs and their temperature-programmability. ,,, Note, compressive stretch ratio (%) was reported, which is the ratio between of the final length (l) to the initial length (L) of the sample after compressive deformation.…”

Influence of Programming and Recovery Parameters on Compressive Behaviors of 4D‐Printed Biocompatible Polyvinyl Chloride or Vinyl–Poly(ε‐Caprolactone) Blends

“…Lower programming temperatures and higher imposed strains cause microcracks and damage in the PC SMP, while higher programming temperatures weaken SME. SME of PVC-based blends, [22][23][24][25] and thermoset PVC networks [26,27] have been proved by some researchers.…”